The use of radio frequency identification (RFID) to identify one of a plurality of items is well known. Typical radio frequency identification (RFID) tags or integrated circuits include a microprocessor, also known as a microchip, electrically connected to an antenna. Alternatively, the microchip is first attached to a pad having electrical leads that provides a larger attachment of “landing” area. This is typically referred to as a “strap” or “interposer.” The strap is then attached to the antenna.
The microprocessor stores data, which can include identifying data unique to a specific item, which is transmitted to an external receiver for reading by an operator and processing of the item. RFID tags can be attached to items for inventory control, shipment control, and the like. RFID tags are particularly useful in identifying, tracking and controlling items such as packages, pallets, and other product containers. The location of each item can be tracked and information identifying the owner of the item or specific handling requirements can be encoded into the RFID and later read by a scanning device capable of decoding and displaying the information.
Many of the processes used to make RFID tags involve applying a material, typically a conductor such as copper, aluminum or an ink containing silver in a binder, to a substrate and then forming it into a desired antenna shape. Typically, any material that remains on the substrate after the antenna shape is formed is then removed or pulled off using any of a variety of techniques, such a process is known as matrix or scrap removal. The material is removed such that the antenna does not short itself out. For example, in etching, the pattern is defined by an etch resist material and the unwanted conductor is dissolved using chemicals. Another such method is die cutting as described in co-pending application US 2007/0171129, filed Jan. 24, 2006 and entitled “Radio Frequency (RF) Antenna Containing Element and Methods of Making the Same” (assigned to the same assignee—Avery Dennison Corporation—as the present application) which is hereby incorporated by reference herein as is necessary for a complete understanding of the present invention. However, for a variety of RFID end use designs and applications, the antenna can be complex, intricate and delicate, for example varying in size and shape, and having different properties depending on the material from which it is formed. Thus, conventional die cutting following the formation of an RFID device, where a portion of the material is pulled out of a web, are unsuitable for spiral coils and designs requiring small gaps as the material to be pulled out (matrix) is too complex or thin in sections and will break if pulled. In addition, portions of the material that are intended to be removed may not be attached to the larger matrix and as such may not be removed completely during a die cutting operation thus creating a short in the device.